Haha.
$5k per month is more than enough. If you spend wisely you should be able to save 30-40% of your salary per month. I've been living in Melbourne for 5 years or so, graduated in 2008 and been working for 2 years.

I buy most of my stuffs in Malaysia (clothes, watch, accessories etc, they are 3 times cheaper back home). The cheapest meal you can get here cost you around AUD$10.00. If you prepare your own meals, obviously it'll be 50% cheaper. Rental is about $150-200 per week. Public transport is about $100+ per month.

For me after living here for so long, I feel home sick all the time, home is still home. I'm working in the health industry, after meeting so many aussies/ ABCs from different background, I am not sure if this is a good place for me to raise a family (I'm getting married next year). Low moral value, low family value, quite sad etc. But if you are still young, I guess this is a good place to earn and to learn, you'll get more opportunities here, australia value talents, if you are good, you will do very well here. Not like Malaysia, too many redtapes, racism is everywhere.